emonTX / RX consistancy of data sends

Hi All,

Firstly, thanks for the great site, info and hardware! I recently bought my modules and they are super, love it!

The question I have is that, my emonTx, the LED flashes when sending data. This happens consistently on a 5 second interval.

The trouble is that I do not receive data on the RX side, every time. At times, I have a 30 to 40 second gap. The LED on the RX side flashes when I receive data on the Raspberry PI. I monitor the serial port and can see the data come in, in sync with the TX side. At times, the TX flashes and nothing on the RX side and nothing on the serial port side.

I have the 433Mhz V2.2 emonTx. I am using my own python code to read the serial port for now, but besides that, the LED on the Rx side should flash in sync with the Tx side. The modules are right next to each other. I have also tried them in a different location, in case of interference, but the same thing happens.

Any ideas?

PS: I have not upgraded or flashed the Rx Raspi Shield.

Robert Wall's picture

Re: emonTX / RX consistancy of data sends

I did read somewhere that you can have problems when the modules are close because the receiver can be overloaded. I regularly use and emonTx and nanodeRF at 868 MHz only a few inches apart and I've never seen a problem, but it's worth trying them further apart if you haven't done so already. I know nothing about the RPi so your problem might be there instead/as well.

QuentinInSA's picture

Re: emonTX / RX consistancy of data sends

Hi Robert,

Thanks for your reply. I have also thought that and tried it from a different room. About 10m away and the same thing. I have tried playing with the code and adding delays etc incase the RF cannot complete in time etc.

It would however appear that I have worked it out. By the looks of things, I had not set the node ID, group and Freq upon start up. I have added the following to my python code just after opening the serial port:

serial.write('9i')  #node 9/Tx is 10

serial.write('4b') #freq 433

serial.write('210g') # to match Tx group ID

serial.write('500l') # show Rx LED to acknowledge settings (500L)

appears to be on a very close 5-6 second interval now!

Robert Wall's picture

Re: emonTX / RX consistancy of data sends

Oops! Not setting the receiver correctly might just have a bearing on the issue.  ;-)

You certainly need the frequency and group, but probably not the nodeID, as the protocol uses the nodeID to identify the transmitter, not the destination. You might want to read RFM12B - Part 2 - Sending Data Between Modules in Building Blocks.

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